<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8" />
    <title>Hello React!</title>
    <script src="https://cdn.staticfile.org/react/16.4.0/umd/react.development.js"></script>
    <script src="https://cdn.staticfile.org/react-dom/16.4.0/umd/react-dom.development.js"></script>
    <script src="https://cdn.staticfile.org/babel-standalone/6.26.0/babel.min.js"></script>
</head>

<body>

    <div id="example"></div>
    <script type="text/babel">
        //创建组件
        //创建组件
        class Count extends React.Component {
            //构造器
            constructor(props) {
                console.log('Count---constructor');
                super(props)
                //初始化状态
                this.state = { count: 0 }
            }
            //加1按钮的回调
            add = () => {
                //获取原状态
                const { count } = this.state
                //更新状态
                this.setState({ count: count + 1 })
            }
            //卸载组件按钮的回调
            death = () => {
                ReactDOM.unmountComponentAtNode(document.getElementById('test'))
            }
            //强制更新按钮的回调
            force = () => {
                this.forceUpdate()
            }
            //若state的值在任何时候都取决于props，那么可以使用getDerivedStateFromProps
            static getDerivedStateFromProps(props, state) {
                console.log('getDerivedStateFromProps', props, state);
                return null
            }
            //在更新之前获取快照
            getSnapshotBeforeUpdate() {
                console.log('getSnapshotBeforeUpdate');
                return 'atguigu'
            }
            //组件挂载完毕的钩子
            componentDidMount() {
                console.log('Count---componentDidMount');
            }
            //组件将要卸载的钩子
            componentWillUnmount() {
                console.log('Count---componentWillUnmount');
            }
            //控制组件更新的“阀门”
            shouldComponentUpdate() {
                console.log('Count---shouldComponentUpdate');
                return true
            }
            //组件更新完毕的钩子
            componentDidUpdate(preProps, preState, snapshotValue) {
                console.log('Count---componentDidUpdate', preProps, preState, snapshotValue);
            }
            render() {
                console.log('Count---render');
                const { count } = this.state
                return (
                    <div>
                        <h2>当前求和为：{count}</h2>
                        <button onClick={this.add}>点我+1</button>
                        <button onClick={this.death}>卸载组件</button>
                        <button onClick={this.force}>不更改任何状态中的数据，强制更新一下</button>
                    </div>
                )
            }
        }

        //渲染组件
        ReactDOM.render(<Count count={199} />, document.getElementById('example'))

    </script>

</body>

</html>